Stringed musical instrument with amplifier



Apwfill 28, 1936,, T. KORHONEN STRINGED MUSICAL INSTRUMENT WITH AMPLIFIER Filed March 22 w L, flrT/S.

Patented Apr. 28, 1936 UNITED STATES PATENT OFFICE Toivo Korhonen,

Vaino Tammenoksa,

Application March In Germany 7 Claims.

This invention relates to stringed musical instruments with amplifier.

Heretofore musical string-instruments have been made in which by means of lever systems the vibrations of the strings are transferred to the membrane of a sound-box for their intensification. In such instruments either no soundingboard or sounding-body is used, or the levers for transferring the string vibrations are rigidly connected with the bridge of the instrument in such a manner that the vibrations are transferred to the membrane from the sounding-board. In the first mentioned construction the instrument has a strange appearance and is often provided with a single string only; in the latter case the membrane and the sounding board vibrate independently of each other, thereby causing disturbances to occur.

One of the objects of the present invention is to provide an instrument in which these disadvantages are avoided, and the appearance hardly deviates from the ordinary, and by which a pure tone, free from disturbances, will be obtained.

According to this invention, to the membrane of a sound-box placed in the interior of a violin, banjo, or guitar shaped instrument, a suitably bent or bell crank lever is connected. The other end of this lever is provided with a suitable abutting surface tightly pressed against the inner side of the sound-board beneath the bridge, and more exactly opposite the high-tone strings of the instrument. By this arrangement not only the vibrations of the strings, but also those of the whole instrument with the sound-board, are transferred uniformly to the membrane and repeated by it, thus giving a pure and undisturbed tone.

The cover of the sound-body, that is the soundboard, is preferably made of an elastic material such as leather, and the sound box is arranged so as to he movable together with the lever, for instance, by means of a screw or the like whereby it may be more or less strongly pressed against the sound-board. Thus changes in the soundboard, which are often caused by atmospheric conditions, may be compensated.

The horn of the sound-box is preferably placed in the interior of the sound-box with its end opening at the lower end of the instrument. This opening is protected by a guard plate bent more or less in the shape of this part of the instrument and attached to the elongated bottom of the sound-body so that a sound-opening is formed by a gap between this plate and the corresponding end of the instrument. The instrument thus has LIFIER Tampere, Finland, assignor to Lappeenr anta, Finland 22, 1934, Serial No. 716,792

December 19, 1933 an appearance hardly differing from the ordinary type to which the invention is applied.

An instrument made in this manner permits the nature of the sound to be changed in a variety of ways with the aid of clamps or mutes, or the like, of different materials, arranged on either the bridge or the strings beyond the bridge; and by the employment of difierent kinds of membranes in the sound box, one is able to obtain not only the timbre of a violin or a violincello, but even the timbre of diiierent wind-instruments, such as the organ and the concertina.

One embodiment of the invention is illustrated in the accompanying drawing wherein Fig. 1 is a longitudinal section of the instrument and Fig. 2 a detail view showing a suitable form of lever for transferring the vibrations to the membrane. In the drawing 1 is the bottom of the sound body, the lower end of which slightly projects over the side panel 2. On this end of the instrument the side panel is cut open so that an opening 3 is made, in which a suitably formed horn 5 ends. This horn is connected with the sound-box 4 and placed inside the sound-body. At the exterior end of the bottom 5 is attached a guard plate 6 which runs parallel with the opposite part of the side panel and leaves free a gap 1 between the side panel part and the guard plate, through which gap the sounds leaving the opening 3 are directed. The sound-box 4 is supported in such a manner that by means of a screw 8 or the like it can be raised or lowered as desired. The screw 8 is preferably arranged in such a way that by means of known transmissions, it may be actuated by a key or the like (not illustrated in the drawing) from the outside. The screw 8 causes the moving of the sound-box by aid of an intermediate spring bow IU, in order to obtain necessary freedom of movement.

To the membrane ll of the sound box 4 one arm of a two-armed or bell crank i2 is attached, which, for the purpose of an easier movement, is supported from a part I3 shaped in the form of a knife-edge which engages a corresponding groove M in a support I5 attached to the soundbox. In order to prevent accidental removal at slack sound-board, the support I3 is pressed against the support I5 by means of a spring l6.

On the second arm of the lever I2 is formed a suitable supporting face l1 which in consequence of a lifting of the sound-box 4 by the screw 6 and the spring I0 is more or less firmly pressed against the underside of the soundboard 9. To counteract the pressure against the membrane effected by the sound-board 9 th ough the lever [2, a spring 23 may be used, connected in a suitable manner to the arm of the lever secured to the membrane, which spring draws the lever outwards in a contrary direction. The sound-box 4 is arranged in such a way that the supporting surface of the lever is lying under the bridge I8 on the sound-board and preferably even underneath the part of the bridge over which the high strings of the instrument are stretched.

A tension ring 20 and a tension screw 2| are for regulating the tension of the sound-board 9 which, as herein described, is made of leather, and a supporting foot 22 of the instrument in this case is constructed similar to a cello. Interchangeable hard steel plates of different thickness and different hardness are preferably used as membranes in the sound-box, whereby, as already mentioned, the sound of the instrument may be changed in a variety of ways.

Without further analysis the foregoing will so fully reveal the gist of this invention that others can by applying current knowledge readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention, and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalency of the following claims.

What I claim as my invention and desire to secure by Letters Patent is:

1. A stringed musical instrument comprising a sound body having an opening in one wall, a bridge thereupon, strings stretched upon this bridge on the exterior of the sound body, a sound box having a membrane, a two armed lever with one arm secured to the membrane and the other arm against the wall of the sound body underneath the bridge, and a funnel leading from the sound box and ending in the opening in the wall of the sound body.

2. A stringed musical instrument comprising a sound body having an opening in one wall, a bridge thereupon, strings stretched upon this bridge on the exterior of the sound body, a sound box having a membrane, displaceable in relation to vibrations of the sound board, a spring connected with the sound box, a two armed lever with one arm secured to the membrane and the other arm abutting against the wall of the sound body underneath the bridge, and a funnel for the sound box ending in said opening in the wall of the sound body.

3. A stringed musical instrument comprising a sound body having an opening in the lower end wall, a bridge thereupon, strings stretched over this bridge on the exterior of the sound body, a sound box having a membrane displaceable in relation to vibrations of one wall of the sound body, a spring on the sound box, a two armed lever engaged by said spring with one arm secured to the membrane and the other arm abutting against the sound board underneath the bridge, and a funnel for the sound box ending in said opening in the lower end of the instrument, a guard plate running parallel to this opening, and providing an open gap between the guard plate and the side wall near the place of the opening.

4. A stringed musical instrument comprising a sound body having an opening in one wall, a bridge thereupon, strings stretched over this bridge on the exterior of the sound body, a sound box having a membrane displaceable in relation to vibration of one wall of the sound body, a spring connected with the sound box and fixed thereto, a support on the sound box, a two armed lever secured to this last-named support with one arm secured to the membrane and the other arm abutting against the sound board underneath the bridge, and a funnel for the sound box ending in said opening in the wall of the sound body.

5. A stringed musical instrument comprising a sound body having an opening in one wall, a bridge thereupon, strings stretched over this bridge on the exterior of the sound body, a sound box having a membrane displaceable in relation to vibrations of one wall of the soundbody, a spring connected with the sound box, a support provided with a track and attached to the sound box, a two armed lever having a knifeedge shaped portion secured to this last-named support with one arm secured to the membrane and the other arm abutting against the sound box underneath the bridge, said spring being helical and between the end of the lever arm fixed to the membrane and the sound body, and a funnel for the sound box ending in the open ing in the wall of the sound body.

6. A stringed musical instrument comprising a sound body having an opening in one Wall and a sound board of elastic material, a bridge thereupon, strings stretched over this bridge on the exterior of the sound body, a sound box having a membrane displaceable in relation to vibrations of the sound board, a spring connected with the sound box, a notched support attached to the sound box, a two armed lever having a knife edge shaped portion resting in said notched support, one arm being secured to the membrane and the other arm abutting against the sound board underneath the bridge, said spring extending between one end of the two armed lever fixed to the membrane and the sound body, and a funnel for the sound box ending in an opening in the wall of the sound body.

7. A stringed musical instrument comprising a sound body having an opening in one wall with a sound board of elastic material, a bridge thereupon, strings stretched over this bridge on the exterior of the sound body, a sound box having one of several exchangeable membranes of different thickness, a support thereon, a two armed lever secured to this support with one arm secured to the membrane and the other arm abutting against the sound board underneath the bridge, a spring between the two armed lever fixed to the membrane and the sound body adapted to counteract the pressure of the sound board against the lever, and a funnel for the sound box ending in said opening in the wall of the sound body.

TOIVO KORHONEN. 

